[Remoting Android] Move pairing secret fetcher to the network thread

remoting/client/jni/jni_client.cc

Index: remoting/client/jni/jni_client.cc
diff --git a/remoting/client/jni/jni_client.cc b/remoting/client/jni/jni_client.cc
index 0787236de5e608ca0ea765b98dbb093294fdfd11..d9885218baf5f040f791de3d69dd923e7cfac181 100644
--- a/remoting/client/jni/jni_client.cc
+++ b/remoting/client/jni/jni_client.cc
@@ -60,11 +60,14 @@ void JniClient::ConnectToHost(base::WeakPtr<JniDisplayHandler> display_handler,
 void JniClient::DisconnectFromHost() {
   DCHECK(runtime_->ui_task_runner()->BelongsToCurrentThread());
   display_handler_ = nullptr;
-  secret_fetcher_.reset();
   if (session_) {
     session_->Disconnect();
     runtime_->network_task_runner()->DeleteSoon(FROM_HERE,
-                                                 session_.release());
+                                                session_.release());
+  }
+  if (secret_fetcher_) {
+    runtime_->network_task_runner()->DeleteSoon(FROM_HERE,
+                                                secret_fetcher_.release());
   }
 }